pregn-4-ene-3,20-dione

Absorption：Rapidly absorbed from the GI tract (oral, IM). T max is 1.5 to 2.3 h (oral); 6.8 h (8% gel); 9.2 h (90 mg IM); 19.3 h (insert). C max is 17.3 to 60.6 ng/mL (oral); 14.9 ng/mL (8% gel); 53.8 ng/mL (90 mg IM); 19.9 ng/mL (insert). AUC is 43.3 to 175.7 ng•h/mL (oral); 1,378.9 ng•h/mL (IM 90 mg); 296.8 ng•h/mL (8% gel); 316 ng•h/mL (insert).

Distribution：Protein binding is 96% to 99%, primarily to serum albumin (50% to 54%) and transcortin (43% to 48%).

Metabolism：Metabolized in the liver to pregnanediols and pregnenolones, which are conjugated to glucuronide and sulfate metabolites.

Elimination：Excreted in the kidney (50% to 60% metabolites), bile/feces (approximately 10% metabolites), and small amount as unchanged in the bile. Absorption t ½ is 25 to 50 h (gel). Elimination t ½ is approximately 19.6 h (IM) and 34.8 h (gel).

Special Populations：
Renal Function Impairment
Use with caution and only with careful monitoring because metabolites are eliminated this way.

Hepatic Function Impairment
Contraindicated.

如果每個月的治療週期開始的太早，尤其是早於月經週期的第十五天前給藥，則可能造成經期縮短或出血。

此外若劑量太高則可能會發生昏睡、嗜睡的情形，一旦降低劑量，則此副作用即消失，不會減低療效。

CYP3A4 inhibitors (eg, ketoconazole)
May inhibit progesterone metabolism, increasing plasma levels and the risk of adverse reactions.

Rifamycins (eg, rifampin)
Progesterone levels may be reduced, decreasing the efficacy.

本藥品不能用於防止懷孕及作為避孕藥使用。